Health risk assessments of heavy metal exposure via consumption of marine mussels collected from anthropogenic sites

Highlights

• Human health risk assessments of heavy metals in Perna viridis were investigated.

• All metals in the mussels were below the established seafood safety guidelines.

• Pb in mussels could easily reach the percentage of prescribed PTWI value of Pb.

• Potential health risk with Pb exposure was found for the mussel consumers.

• Consumption rate of mussels should be limited to minimize the metal health risks.

Abstract

A total of 40 marine mussel Perna viridis populations collected (2002–2009) from 20 geographical sites located in two busy shipping lanes namely the Straits of Malacca (10 sites; 16 populations) and the Straits of Johore (8 sites; 21 populations) and three populations (2 sites) on the east coast of Peninsular Malaysia, was determined for Cd, Cu, Fe, Ni, Pb and Zn concentrations. In comparison with the maximum permissible limits (MPLs) set by existing food safety guidelines, all metal concentrations found in all the mussel populations were lower than the prescribed MPLs. In terms of the provisional tolerable weekly intake prescribed by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) and oral reference doses (ORDs) by the USEPA, all the studied metals (except for Pb) were unlikely to become the limiting factors or unlikely to pose a risk for the consumption of the mussel populations. The estimated daily intake (EDI) for average level mussel (ALM) and high level mussel (HLM) consumers of mussels was found to be lower than the ORD guidelines for Cd, Cu, Fe, Ni and Zn. Furthermore, the target hazard quotient (THQ) was found to be less than 1 for ALM consumers but higher than 1 for HLM consumers in some sites. Therefore, there were no potential human health risks to the ALM consumers of the mussels. However, for Pb THQ values, the Pb levels in some mussel populations could create a health risk problem. Present results indicate that the consumption amounts of mussels should be limited for minimizing potential health risks of heavy metals to the HLM consumers.

Introduction

The Straits of Malacca (SOM) is one of the busiest shipping lanes in the world while the Straits of Johore (SOJ) is a semi-enclosed ecosystem strait, bordering between southern Peninsular Malaysia (PM) at Johore and Singapore Island. Both Straits have received waste discharges from both land- and sea-based sources, as well as natural and anthropogenic sources (Yap et al., 2003a). They are very sensitive to contamination which primarily comes from the mainland via rivers or canals due to various human activities and shipping activities. These wastes might potentially contain hazardous substances which are harmful to both human health and marine ecosystem. Previous studies showed that contributions of heavy metals (Yap and Pang, 2011, Yap and Wong, 2011) were related with pollution sources in the SOM. Similarly for SOJ, elevation of hazardous substances into the area has also been reported previously (Eugene Ng et al., 2013, Yap et al., 2012a).

Heavy metals are one of the major pollutants firstly proposed by Goldberg (1975) to assess the health of the ocean through a Mussel Watch Programme (MWP). Later, Farrington et al. (1983) strongly supported the MWP proposal by highlighting the bivalves as ideal surveillance tools to monitor coastal pollution. They reasoned that bivalves 1) have a widespread distribution across the world's coastal waters, 2) are sedentary, 3) concentrate pollutants by factors of a thousand to a hundred thousand, 4) appear to be resistant to pollutants, 5) are commercial products and, 6) are consumed extensively in some areas of the world, and hence pose a risk to human health. The essential keyword from the above statement was ‘pose a risk to human health’ because humans are the eventual benefactor from the consumption of the natural marine resources. As a matter of fact, the use of mussels to monitor coastal pollution is both widely and broadly accepted by many researchers around the world (Liu and Kueh, 2005, Sasikumar et al., 2006, Szefer et al., 2004). The reliability of the mussel Perna viridis as a biomonitor of metal contamination has been mainly summarized by Yap (2012) from Malaysia. Considering that P. viridis is edible and marketed commercially, the measurement of metal levels in the soft tissues (STs) are of public concern because excessive consumption of metal-contaminated mussels could result in toxicity to consumers (Jovic and Stankovic, 2014).

With the increasing trend of the incidence rate of cancers among human populations in the world, more efforts and costs for prevention and control of the cancerous diseases shall be paid (Zheng et al., 2015). The main source of human exposure to different essential metals is through the food chain by seafood consumption and it can contribute to achieving the recommended levels of daily intake of trace metals. Therefore, human health risk assessment (HHRA) of exposure to heavy metal risks is of paramount importance (Bilandzic et al., 2014, Jovic and Stankovic, 2014). From the literature, there have been no reports on the HHRA of heavy metal exposure in P. viridis from the SOM and SOJ. Therefore, the objectives of this study were to evaluate the HHRA of Cd, Cu, Fe, Ni, Pb and Zn, associated with the consumption of wild and farmed P. viridis collected from SOM and SOJ.